Barcelona stars Gerard Pique and Alex Song appear to have been scrapping while on top of the team's double-decker bus to celebrate their La Liga triumph.

In these astonishing pictures, former Arsenal midfielder Song and Pique seem to be fighting while the bus makes its way around the Catalan city.

Club captain Carles Puyol and goalkeeper Victor Valdes look to be playing peacemakers in the end, but appear to be having a heated discussion of their own in the background as their team-mates grapple in front of celebrating supporters.

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Astonishing: Gerard Pique (right) and Alex Song seem to be fighting on top of the Barcelona bus

Larking about? Song grabs Pique's arm and seems to be cocking his fist ready to throw a punch

Defence: Pique appears to hold his hands up to stop Song as the bus made its way round the city

At one point, Song is seen grabbing Pique's arm and cocking his clenched fist as if readying himself to throw a punch at the Spain defender.

The former Manchester United centre half winces while holding his arms up in defence.

In another shot, Song is captured landing an open-handed slap on his team-mate as Puyol and Valdes watch.

The bus tour was a raucous affair with video footage emerging of the players drinking and partying as the bus travels around the city and police picking up empty bottles from the streets.

Happy? Other Barcelona stars turn to watch as Song and Pique continue to tussle

Caught flush: Song seems to land a slap on Pique's cheek during the scuffle

There is a possibility that the superstars are simply larking about as footage shows how the bus parade turned into a party with plenty of beer-drinking on show from the Spanish champions.

But based on these images, the pair look to be seriously quarrelling atop the coach. Although the scuffle went unnoticed on Monday afternoon, politicians in Catalonia have complained that drinking on the bus was setting a bad example to young fans who watched their title-winners parade the trophy.

The parade was to honour Barca reclaiming their La Liga crown from Real Madrid, after mounting a 10-point lead with three games to play.

Barcelona held their end-of-season awards dinner last night, and Song, who left Arsenal for Spain last summer did not appear in any of the pictures released.

Heated? Puyol and Valdes talk between themselves as the scuffle diffuses

Song, who operates as a holding midfielder, has made 19 appearances since joining last August.

Before Song's move to La Liga, Pique went public about how he had followed the Cameroon man's career closely and would welcome him to the Nou Camp.

Speaking to El Mundo Deportivo, the defender noted how Song had developed under Arsene Wenger into a ‘very good player’.

‘He is physically very strong and is good with the ball at his feet. We are open to his arrival. If he comes, and from what I have read he could do, we would love to have him.’

But Song has struggled to force his way into a midfield that boasts world-class talents Xavi, Sergio Busquets and Cesc Fabregas and was in January voted one of the worst signings of the season behind Real Madrid's Luka Modric.